Tuning Nanocrystal Surface Depletion by Controlling Dopant Distribution as a Route Toward Enhanced Film Conductivity
| Autor: | Uwe Kortshagen, Corey M. Staller, Zachary L. Robinson, Benjamin L. Greenberg, Stephen L. Gibbs, Ankit Agrawal, Sebastien D. Lounis, Delia J. Milliron |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Oxide chemistry.chemical_element FOS: Physical sciences Bioengineering 02 engineering and technology Conductivity 010402 general chemistry 01 natural sciences Molecular physics Atomic layer deposition chemistry.chemical_compound Mesoscale and Nanoscale Physics (cond-mat.mes-hall) General Materials Science Surface states Condensed Matter - Materials Science Dopant Condensed Matter - Mesoscale and Nanoscale Physics Mechanical Engineering Materials Science (cond-mat.mtrl-sci) General Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Electron localization function 0104 chemical sciences chemistry Nanocrystal 0210 nano-technology Indium |
| Popis: | Electron conduction through bare metal oxide nanocrystal (NC) films is hindered by surface depletion regions resulting from the presence of surface states. We control the radial dopant distribution in tin-doped indium oxide (ITO) NCs as a means to manipulate the NC depletion width. We find in films of ITO NCs of equal overall dopant concentration that those with dopant-enriched surfaces show decreased depletion width and increased conductivity. Variable temperature conductivity data shows electron localization length increases and associated depletion width decreases monotonically with increased density of dopants near the NC surface. We calculate band profiles for NCs of differing radial dopant distributions and, in agreement with variable temperature conductivity fits, find NCs with dopant-enriched surfaces have narrower depletion widths and longer localization lengths than those with dopant-enriched cores. Following amelioration of NC surface depletion by atomic layer deposition of alumina, all films of equal overall dopant concentration have similar conductivity. Variable temperature conductivity measurements on alumina-capped films indicate all films behave as granular metals. Herein, we conclude that dopant-enriched surfaces decrease the near-surface depletion region, which directly increases the electron localization length and conductivity of NC films. |
| Databáze: | OpenAIRE |
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